Milling-machine



(No Model.) A. T. GIFPORD. MILLING MACHINE.

No. 432,936 Patented July 22, 1890.

W44. ZJMmyQZ/L UNITED STATES PATENT FFICE.

ALENZA T. GIFFORD, OF HOPEDALE, MASSACHUSETTS.

MILLING-MACHINE.

SPECIFICATION forming part of Letters Patent No. 432,936, dated July 22, 1890.

Application filed August 22, 1889. Serial No. 321,664- (N'o model.)

To all whom it may concern.-

Be it known that I, ALENZA T. GIFFORD, of l-Iopedale, in the county of \Vorcester and State of Massachusetts, have invented an Improvement in lVIilling-ltlachines, of which the following is a specification.

The nature of my invention consists in the improved combination of the revolving cutter with the carriage-bed, and means for operating the same, as hereinafter set forth.

Figure 1 is a side elevation and partial section illustrating my improvement. a plan view of the under side of the carriage and of the carriage-operating mechanism. Figs. 3 and 4 are views, partly in section, illustrating the proper action of a revolving cutter in performing its work.

In the accompanying drawings, Figs. 3 and 4, A is the cutter-arbor of a milling-machine, upon which the cutter B is secured by means of the nut O.

D is the piece of work in which a groove or channel a is to be cut; and in performing work of this kind on a milling-machine, as ordinarily constructed, it has been the universal practice to move the piece of work D in a direction contrary to the movement of the under side of the cutter, as shown by the arrows in Fig. 3; but I have found by experiment that the action of the cutter, when so operated, is such as to cause a slight chatter, which results in the production of a comparatively uneven. surface, the chips from the cutter being liable to interfere with the cutterteeth in obtaining a proper hold upon the metal in front of the same; and I have also discovered by practical experiment that when the piece of work and the bottom edge of the cutter are made to move in the same direction, as shown by the arrows in Fig. 4, the chips carried over with the teeth of the cutter Will not interfere with the production of .uniformly smooth work 5 and, furthern1ore,in cutting grooves having comparatively thin partitions between them, the cutter, when revolved as shown in Fig. 3, would tend to cause the partitions to spread away from the cutter, whereas, when revolved as shown in Fig. 4, the thin partitions between the parallel grooves would be kept in true line and in perfect condition, and in order to adapt a Fig. 2 is.

milliug-machine for the use of a cutter revolving as shown in Fig. 4, it is necessary to hold the carriage firmly in both directions of its movements without backlash, and to this end I secure the worm-gear E upon the shaft F between the wheels G G, which are secured to the same shaft. Upon the peripheries of the wheels G l are placed the flexible metallic straps H H or their equivalent chains, which are securely held to the periphery of the wheels by means of the screws b. The strap H passes from the screw 2) partially around the periphery of the wheel G, and is secured to the under side of the carriage I by means of the screw 0, and the strap H passes from the screw 1) partially around the wheel G, and is provided at its outer end with the sleeve d, having an internal screw-thread adapted to receive the tightening-screw e loosely held within the bore of the lugf, which may be made integral with the bed of the carriage.

Upon the front end of the shaft F is secured the hand-wheel J, by means of which hand movement may be imparted to the carriage, and to theshaft K, directly under the worm-wheel E is secured the worm L, and to the opposite end of the shaft K is secured the cone-pulley M, adapted for driving the carriage at different rates of speed. The shaft K is held at one end inthe pivoted box N in order that the worm may be thrown out of gear with the wheel E by lowering the end of the shaft upon which the worm is secured.

In Figl 1 the cutter 13, which is held upon the arbor A, is represented as cutting a groove 9 in a cylindrical bar 0, which is held, as usual, upon centers h It firmly attached to the carriage-bed I, the arbor and cutter being made to revolve in the direction indicated by the arrow above the cutter, and the piece of work 0 being fed to the cutter by means of the worm and worm-wheel in the direction of the arrow shown under the bar.

It will be readily seen that when the cutter is made to revolve, as above described, in the direction of the feeding-movement of the work, the cutter will be liable to ride out of the groove g either to the injury of the cutter or to the piece of work,a slight amount of backlash in the movement of the carriage being suflicient to cause this injurious result; but it will be clearly seen in Fig. 1 that by means of the wheels G G and the flexible metallic straps H H, the tension of which may be adjusted by means of the tightening-screw e, the carriage I can be operated from the shaft F through its whole extent of movement without backlash, so that the work 0, when firmly held upon the bed of the carriage, will not be liable to be drawn under the cutter by its cutting action upon the forward feeding-movement of the carriage, thus permitting the work to be advantageously performed with the cutter revolving in the direction of the carriage.

In order to prevent the Wear of the box N by the backward thrust of the worm L,I provide a flat spring P, which is arranged to press with considerable force against the end i of the shaft K; and in order to hold the Worm L in close yielding engagement with the teeth of the worm-gear E, I provide a flat spring Q, which presses upward upon the movable bearing-box N. The worm L may be disengaged from the teeth of the wormwheel E by means of the sliding bar R, provided with a roller 3, which engages with the inclined surface If upon the sliding box N.

I claim as my invention-- 1. The combination, with the feeding-carriage and the rotary cutterarranged to make the cut in the same direction with the feed ing-movement of the carriage, of the worm, the worm-wheel, and the opposite bands, which are adapted to feed the carriage in the same direction with the operating movement of the cutter-teeth, substantially as described.

2. The combination, wit-h the cutter, the feeding-carriage, the worm, and worm-wheel, of the opposite bands or chains adapted to move the carriage by the simultaneous winding up of one band or chain and the equal unwinding of the other, and a spring for preventing the end-thrust of the worm in one di- ALENZA T. GIFFORD.

\Vitnesses:

SOCRATES SCHOLFIELD, JEROME O. TAFT. 

